Information about the series: Language plays a central role in conveying mathematical content. For children with a non-German native language or those requiring additional language support, this often lies at the root of seemingly mathematical problems. In response to this issue, eins-zwei-drei is the first teaching resource to systematically address it: It combines mathematical subject content with systematic language support, ensuring that all children meet educational standards in mathematics. To achieve this, eins-zwei-drei offers child-friendly language models, systematic development of mathematical vocabulary, clear explanation phases for introducing new content, carefully formulated mathematical tasks that consider linguistic pitfalls, extensive information on these pitfalls, and practical teaching suggestions in the teacher's materials.